A quality prosthetic hand cost tens of thousands of dollars…until the advent of 3D printing. Now we’re entering an age when so many machines can be produced at low cost.

12-year old Leon McCarthy of Marblehead, Massachusetts was born without fingers on his left hand. He didn’t have a functional prosthetic replacement until his father, Paul McCarthy, found online instructions for a design that could be built with a 3D printer. Leon’s school had a $2,500 3D printer. For just $5-10 of materials, they built a useful mechanical hand. As he moves his wrist forward, the fingers clench. As he moves it back, the fingers open.